A piezoelectric thin film including scandium aluminum nitride (ScxAl1-xN; 0<x<1) is capable of exhibiting a higher piezoelectric coefficient for example than an aluminum nitride thin film and the like. Therefore, it is expected that a piezoelectric thin film will be applied to a surface acoustic wave (SAW) element, a light-emitting layer for a light-emitting diode (LED) having a wide emission wavelength range, a microelectromechanical systems (MEMS) element and the like.
A piezoelectric thin film including scandium aluminum nitride is produced by sputtering scandium and aluminum on a substrate in a nitrogen atmosphere (see Patent Literature 1).